Data storage apparatus controls



Jan. 21, 1964 J. M. COOMBS 3,119,110

DATA STORAGE APPARATUS CONTROLS Original Filed May'2, 1949 15Sheets-Sheet 1 Jan. 21, 1964 J. M. COOMBS- 3,119,110

DATA STORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15Sheets-Sheet 2 Jan. 21, 1964 J. M. cooMBs 3,119,110

DATA STORAGE APPARATUS CONTROLS 0rigina1 Filed May 2, 1949 15Sheets-Sheet 5 o o I 44 5o 62 37a 0 44c 4i, 52 \1' so 40" w 'll '1 I "Il|ss D II I h fi Jan. 21, 1964 J. M. COOMBS DATA STORAGE APPARATUSCONTROLS Original Filed May 2, 1949 15 Sheets-Sheet 4 Jan. 21, 1964 J.M. COOMBS 3,119,110

DATA STORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15Sheets-Sheet 5 Jan. 21, 1964 J. M. COOMBS 3, 9 0

DATA STORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15Sheets-Sheet 6 lli' Jan. 21, 1964 J. M. cooMBs 3,119,110

DATA STORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15Sheets-Sheet 7 inmmm- INVENTOR V a J Jan. 21, 1964 J. M. COOMBS DATASTORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15 Sheets-Sheet 9Q new e35 Q INVENTOR.

15 Sheets-Sheet 10 Original Filed May 2, 1949 INVENTOR.

Jan. 21, 1964 J. M. cooMBs 3,119,110

DATA STORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15Sheets-Sheet ll Jan. 21, 1964 J. M. COOMBS 3,119,110

DATA STORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15Sheets-Sheet 12 Jan. 21, 1964 J. M. COOMBS DATA STORAGE APPARATUSCONTROLS l5 Sheets-Sheet 13 Original Filed May 2, 1949 Jan. 21, 1964 J.M. cooMBs 3,119,110

DATA STORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15Sheets-Sheet 14 H. 081 how mmw 20:20 65 M20 23 I IF OmN+ h Ew y M wmw mmJan. 21, 1964 J. M. cooMBs 3,119,110

DATA STORAGE APPARATUS CONTROLS Original Filed May 2, 1949 15Sheets-Sheet l5 VOLTAGE AT READING HEAD DIFFERENTIATED VOLTAGE OUTPUTVOLTAGE United States Patent 3,119,110 DATA STORAGE APPARATUS CUNTRGLSJohn M. Coombs, Poughkeepsie, NFL, assignor to Sperry Rand Corporation,a corporation of Delaware Original application May 2, 1949, Ser. No.90,941. Di-

vided and this application Nov. 12, 1954, Ser. No. 468,455

14 Claims. (Cl. 346-74) The present invention relates to data storageapparatus controls and, more particularly, to means for controlling thedrive of such an apparatus as well as means for controlling thetransmission of data with respect to the drum, tape or other datastorage element of such an apparatus. It will be understood that thetransmission of data with respect to such an element involves therecording of data upon the element, alteration, including erasure, ofdata upon the element, or the reading of data previously recorded uponthe element.

This application is a division of my copending application Serial No.90,941, filed May 2, 1949, and now abandoned.

In various lines of endeavor, for example, computing and recording, itis desirable to store information for a period of time and yet have theinformation readily availale for reading or alteration. Apparatus andsystems for this purpose are disclosed in the application of Arnold A.Cohen, William R. Keye and Charles B. Tompkins for Data Storage Systems,Serial No. 16,998, filed March 25, 1948, now Patent No. 2,540,654, andin the application of John M. Coombs and Charles B. Tompkins for DataStorage Apparatus, Serial No. 16,997, filed March 25, 1948, now PatentNo. 2,617,705.

Although the present invention may be used with various forms of datastorage apparatus, in the embodiment of the invention disclosed hereinfor purposes of example, the data storage element is a rotary drumhaving paramagnetic tapes upon its periphery and with a group of magnetspositioned adjacent each of the tapes to apply or record data or signalsupon the tape, and erase, read or alter such data, all as particularlydescribed in said applications. As is pointed out in said Coombs andTompkins application, the drum used therein may be rotated at such ratethat the drum periphery will have a speed of the order of 400 inches persecond, and with a drum thirtyfour inches in diameter, the trackassociated with each magnet may include 5,340 cells or discrete areas toreceive signals.

During either reading or erasing of signals the drum of saidapplications may be continuously rotated at a speed of the order of 220rpm. As is also mentioned in said applications, signals may be alteredor recorded during rotation of the drum at the high speed mentioned.However, in the original recording of data upon the drum, it isfrequently desirable to move the drum non-continuously, viz., step bystep, and in such a way that a cell or discrete data receiving areathereon will be stationary with respect to a recording magnet for thebrief interval of time required for recording. In addition, it will bedesirable to have all data start, or be located at a predeterminedposition with respect to a given point circumferentially of the drum andthe magnets or other data transmitting members. Therefore, it isdesirable to include controls to bring that starting or homing point ofthe drum into proper position with respect to the magnets. It isdesirable to rotate the drum at somewhat lower speed to bring or homethe drum to such starting point.

An object of the present invention is to provide a driving and controlmeans for a movable data storage element, or other movable element,including arrangements to continuously move the element at high speed orlow speed, or to move it intermittently or step by step.

3,119,110 Patented Jan. 21, 1964 "ice A further object of the inventionis to provide control means whereby the driving means for a data storageelement or other movable element will be operative to provide eithercontinuous or step by step movement.

Still another object of the invention is to provide control meanswhereby a data storage element can be moved to a predetermined positionand then slowly moved, for example, step by step, to finally bring it tothe exact position desired.

Still another object of the invention is to provide control means for amovable data storage element whereby step by step movement of theelement during a recording operation will be synchronized with andcontrolled by the application of data to the element.

Other objects and advantages of the invention will be apparent from thefollowing specification and accompanying drawings, in which drawings:

FIGURE 1 is a front elevation of the apparatus of the 1nvent1on.

' FIGURE 2 is a side view looking toward FIGURE 1 from the left ofthelatter figure.

FIGURE 3 is a rear view of the apparatus.

FIGURE 4 is an elevation of one of the drive mechanisms, the viewlooking toward the apparatus from'the rear and showing, on an enlargedscale, structure partially illustrated at the lower portion of FIGURE 3.

FIGURE 5 is a view of the drive mechanism of FIG- URE 4 looking from theright toward the latter figure. FIGURE 5 is also an enlarged view ofmechanism partially shown at the bottom of FIGURE 2.

FIGURE 6 is a vertical sectional view on the line 66 of FIGURE 5.

FIGURE 7 is a view of the driving mechanism taken on the line 7-7 ofFIGURE 4.

FIGURE 8 is a view on the line 8-8 of FIGURE 4, viz., a bottom view ofthe drive mechanism of FF"- URE 4.

FIGURE 9 is a detail vertical and transverse section on the line 9-9 ofFIGURE 4.

FIGURE 10 is a detail section on the line 10-10 of FIGURE 9.

FIGURE 11 is a fragmentary view showing the manner of supporting amagnetic head with respect to the drum.

FIGURES l2 and 13, together, diagrammatically illustrate drivecontrolling circuits for the data storage element.

FIGURE 14 is a chart indicating the sequence of oper ation of thevarious elements of the circuits of FIGURES 12 and 13.

FIGURE 15 is a diagrammatic showing of the circuits used duringrecording and erasing data upon the data storage element.

FIGURE 16 illustrates a modification of the FIGURE 15 circuit.

FIGURE 17 charts the sequence of operations during recording with thedrum moving step-by-step.

FIGURE 18 is a diagrammatic view showing circuits for use in reading andre-recording information, and

FIGURES 19, 20 and 21 show the voltage characteristics of signalsobtained at stages in the circuit of FIG- URE 18.

Referring to FIGURE 1, the numeral 20 designates a platform, table orthe bottom wall of a cabinet or other support upon which the apparatuswould be positioned. The numeral 22 generally designates the stationaryframe of the apparatus. Frame 22 includes a lower horizontally extendingplate 24 preferably directly secured to the support 20 and also includesfront and rear vertically extending frame walls 26 and 28. As is bestindicated in FIG- URES 1 and 3, the respective front and rear framewalls 26 and 28 may be provided with openings 30 and 32 intermediatetheir ends. The opening 30 at the top of the front frame wall 26 isbridged by a forwardly extending supporting platform 34 for a motor 36,as well as by a support for the front journal 37 for the shaft 37a ofdata storage drum 38. Similarly, as is shown in FIGURE 3, the opening 32in the rear frame wall 28 is bridged by a plate 40 which supports therear journal 42 for the drum shaft 37a, as well as a brake 44hereinafter described. As is best shown in FIGURES 1 and 3, the framewalls 26 and 28 project upwardly at one end thereof as indicated at 46and 48, respectively. These upwardly projecting portions carry crossbars 50 arranged concentrically with the periphery of drum 38. As ishereinafter described, the cross bars 50 support magnets generallydesignated 52.

As is described in said Cohen et al. and Coombs et al. applications, thedrum may have an outside diameter of thirty-four inches ,and a width ofapproximately ten and one-half inches. The drum is formed of aluminum orother non-magnetizable material and will have its periphery covered withmagnetic tape 54, as best shown in FIG- URE 4, the tape being iron oxidecoated paper tape or other suitable tape or coating includingparamagnetic material. A number of signal or data storage tracks wouldbe spaced or located upon the width of the drum so that each trackextends circumferentially of the drum. With a drum 38 having a width often and one-half inches, forty tracks can be provided, with the trackcenter-lines onequarter of an inch apart. By the present invention, theforward edge of the drum 38 is provided with a circumferentiallyextending worm Wheel 56 which comprises an element of one drivearrangement for the drum.

By the system illustrated in the drawings, each track upon the drum 38,other than the timing and control tracks, will have a group of threemagnets 52 associated therewith, the three magnets being respectivelymounted on vertically adjacent cross bars 50 so that they will bespjaced circumferentially of the path of the drum. The uppermost magnet,designated 58, of each group, will be a re-writing or altering magnet,the next lower magnet designated 60 may be used for erasing, as well asfor original or fresh recording or writing, while the lowermost magnet62 of the series is a reading magnet. As is indicated in FIGURE 2,because the magnets must usually be of a greater width than the drumtracks with which they are associated, the three upper cross bars 50carry the magnets for alternate tracks of the drum and the magnets forthe intervening tracks are supported upon the three lower cross bars 50.

FIGURE 11 discloses the manner of mounting each magnet with respect tothe corresponding cross bar 50 and drum 38. A magnet includes two coils,each wound on one of the two cores 64. The cores 64 are supported in anon-magnetic holder 66, the forward gap 58 of the magnet beingpositioned approximately .002 inch from the paramagnetic tape or surface54 of the drum. In order to enable the magnets to be adjusted radiallyas well as circumferentially of the drum, the following mounting for themagnets is provided. A bracket 70 of substantially U- shaped form isfitted in a vertically extending groove 72 provided in the cross bar 50,the lower leg of the bracket being provided with a set screw 74 adaptedto contact with the under surface of the bar so that the position ofbracket 70 can be adjusted vertically of the bar and its magnet therebycan be adjusted circumferentially of the drum 38. A locking bolt 76extends through a slot in the vertically arranged plate of bracket 70and into a bore in bar 50 to lock bracket 70 in adjusted position. Theupper portion 78 of bracket 70 is grooved as indicated at 80 to closelyreceive a magnet holder 82. The holder 82 is provided with a set screw84 at its outer end to enable the holder, as well as the magnet, to beadjusted radially of the drum. A locking bolt 86 extends through a slotin the holder 82 and into a threaded bore in bracket 70 to lock theholder in adjusted position.

Motor 36 illustrated in FIGURES l and 2 is used to drive the drum 33continuously at high speed and with continuous and uniform movement. Themotor performs its driving function through a reduction gearing enclosedin casing 96 and an overrunning clutch enclosed at 92. The motor willusually drive the drum at a speed of the order of 220 rpm. The brake 44shown in FIG- URE 2 is electrically operated to stop rotation of thedrum in a reasonably short time after power to motor 36 has been cutoff. It will be perceived that motor 36 comprises a means to drive thedrum continuously at high speed. Drive of the drum by motor 36 will beused during erasing and reading of data, as well as during altering orre-recording of data.

As is best shown in FIGURES 4 to 8, and particularly in FIGURE 4, withinthe supporting frame 22 and beneath drum 33 a carrier plate generallydesignated 100 is pivoted to the front frame wall 26. The pivot forcarrier plate 100 is a stud 102 extending horizontally and rearwardlyfrom the frame wall 26 so that the carrier plate 100 may have a swingingmovement in a vertical plane lying parallel to the radial faces of thedrum. Stud 162 extends through the frame wall 26 and is secured inposition by a nut 103 bearing against the opposite side of the framewall. It will be observed that carrier plate 100, being pivoted upon theforward frame plate 26, will be positioned substantially beneath theworm wheel 56 of drum 33. This relationship of the carrier plate 100 tothe worm wheel 56 as well as the remainder of the apparatus can best beascertained from FIGURE 2 which shows the plate 100 as viewed from theright of FIGURE 4.

Carrier plate 1% supports various driving connections to rotate drum 38step by step during recording and alteration of data upon the drum. Inaddition, carrier plate 1% supports driving connections to home thedrum, viz., bring a predetermined point on the drum to a recording orwriting starting position with respect to the magnets. This homing driveincludes connections to first move the drum by continuous movement untilit is adjacent starting or home position and then move the drum step bystep through a further brief rotation until the actual home position isreached. These driving connections are discussed in the immediatelyfollowing section, while the controls therefor are discussed under thesection headed Drive Controlling Circuits.

DRIVE ELEMENTS As is best shown in FIGURE 5, the driving connections orelements on carrier 160 are driven from a motor 104 secured to the baseplate 24- of supporting frame 22. It will be noted that a belt 106moving about a pulley 108 011 the drive shaft of motor 104 extends abouta pulley 110 fixed to a shaft 112 journalled in brackets 114 and 115fixed to carrier plate 100. By comparing FIGURES 4 and 5, it will beobserved that the axis of the motor pulley 108 is at right angles to theaxis of stud 102 about which the carrier plate 160 swings. However,because the swinging movement of carrier 100 is very slight and alsobecause the driven pulley 1 10 carried by carrier 100 is closelyadjacent the axis of swinging movement of the carrier, as well asbecause belt 106 is flexible, motor 104 will drive pulley 110 in everyposition carrier 100 can assume.

Carrier 100 is drawn to upward position by spring 107, this movementbeing controlled by a motor 109. Motor 109 also moves carrier 100downwardly, all as hereinafter explained in detail.

As is indicated in FIGURES 4, 7 and 8, the shaft 112 to which pulley 110is fixed extends into a one-revolution clutch, indicated at 116, andactuated by a mechanism 117 controlled by an electromagnet 113. By thisarrangement, when shaft 112 rotates with continuous movement, the drivenshaft 120 connected to the one-way clutch 116 will only be rotated whenthe magnet 118 controlling mechanism 117 has been energized, and, whenmagnet 113 is energized, shaft 126 will only be rotated for a singlerevolution, and will then stop. It will be observed that clutch 116 thuscomprises a periodic engagement clutch.

Shaft 120 is journalled in a bracket 122 fixed to carrier plate 106 andthe opposite end of the shaft (the lefthand end in FIGURES 4, 7 and 8)has a cam 124 fixed thereto. As is best shown in FIGURES 9 and 10, a camfollower or pawl actuator generally designated 126 is associated withthe cam 124, the cam follower including an arm 128 having a pin 130secured at one end thereof and which pin has a roller 132 mountedthereon. A spring 134 extending between the pin 130 and a pin 13:8 fixedto an arm 140 fixed to journal bracket 122 holds the roller 132 inengagement with cam 124. The movement of the arm 128 with respect to thecam is guided by the provision of a slot 142 in arm 128 and which slotrides on shaft 120 adjacent earn 124. The opposite end of cam followerarm 128 is pivotally connected at 143 to an arm 144 pivotally mountedupon the end of a shaft 146 jouinalled in a bracket 148 also fixed tocarrier 1%. As is shown in FIGURES and 4, shaft 146 is parallel to butoffset from the driven shaft 120 which carries cam 124.

A pawl 156 is also pivoted on pin 143. Pawl 150 is normally urged in aclockwise direction as viewed in FIGURE 9 and about its pivot 143 by theaction of a coil spring 152 which extends from the outer end of the pawlto the arm 144. Pawl 150 is adapted to engage a ratchet wheel 154 fixedto the shaft 146.

It will be observed that by the arrangement disclosed in FIGURES 9 and10 and described above, each complete rotation of cam 124 resulting fromthe operation of the one-revolution clutch 116 will cause cam followerarm 128 to be moved upwardly, thereby swinging the pawlcarrying arm 144in a clockwise direction with respect to FIGURE 9 so that pawl 151),being in engagement with ratchet wheel 154, will rotate shaft 146 aslight distance. The spring 152 will be of sufficient strength to holdthe pawl 151) in driving engagement with the ratchet wheel 154 duringthis upward and driving movement of the pawl. During return movement ofcam follower or pawl actuating arm 128, spring 152 will permit the pawl150 to ride back over the teeth of the ratchet wheel. The stroke of thecam follower 128 is only sufficient to advance shaft 146 by the lengthof one tooth of ratchet wheel 154. Ratchet wheel 154 preferably will beprovided with about ten teeth so that its extent of rotation on eachdriving movement of the pawl will be relatively slight and of the orderof 36.

As is hereinafter explained, the pawl 150 can be moved out of engagementwith the ratchet wheel 154 by the action of a pawl throw-out or releasemember 153 in lifting the pawl, viz., rotating it in a counterclockwisedirection on its pivot 143 and against the action of a spring 152. Whenthe pawl is thus lifted it will be disconnected from the ratchet wheel154 and cannot impart any drive to shaft 146.

As is best shown in FIGURES 4, 7 and 8, shaft 146 extends through asecond journal bracket 160 and, immediately beyond that bracket, has acam 162 fixed thereto, the cam including a peripheral tooth or rise 163.The purpose of cam 162 is hereinafter described. Adjacent its oppositeend, shaft 146 is journalled in a bracket 164. Between the journal 164and cam 162, shaft 146 has a worm gear 166 fixed thereto. Worm gear 166is adapted to mesh with the worm wheel 56 fixed to drum 38 when thecarrier plate 161 is swung upwardly on its pivot 102 to a position suchas shown in FIGURE 4. A spring 147 surrounding shaft 146 between journal146 and a collar 147a mounted on the shaft acts as a thrust bearing.

It will be observed from FIGURE 4 that a second worm wheel 16% mesheswith worm gear 166 and that worm wheel 168 is rotatable about an axis170 positioned below worm shaft 166. Worm wheel 168 is an idler androtates in a trough 172 of lubricant to thereby convey lubricant to wormgear 166 and thence to worm wheel 58. A wiper strip 174 pivoted at 176on carrier plate 1651 includes teeth which mesh with the teeth at oneend of worm gear 166 to wipe excess lubricant from the latter and returnit to the trough 172.

If desired, a felt wiper supplied with lubricant can be used tolubricate the worm gearing, instead of the trough 172 and wiper strip174.

Beyond journal bracket 164 (to the left in FIGURES 4, 7 and 8), the wormcarrying shaft 146 extends into an overrunning clutch 178. The othershaft 180 connected with overrunning clutch 178 extends into a driveadaptor comprising an enclosed series of shafts and gears generallydesignated 182. By means of adaptor 182, shaft 136 is drivinglyconnected to a parallel shaft 184 which extends into a magnetic clutch186. It will be perceived that drive adaptor 182 simply comprises meanswhereby the parallel shafts and 184 are drivingly connected for rotationin the same direction. The housing of magnetic clutch 186 is fixed tocarrier plate 100.

As shown in FIGURES 7 and 8, driving connections extend to the rightfrom magnetic clutch 186, these connections comprising an enclosedflexible shaft generally designated by the numeral 188. At its oppositeend flexile shaft 138 is connected to a drive adapter generallydesignated 196 and having the same function as the drive adaptor 1212.Drive adaptor 1213 is connected to the shaft 112 to which pulley 111) isfixed.

It may be generally explained at this point that when the magneticclutch 186 is de-energized or disengaged, rotation of the shaftingwithin the adaptor 190 and the resultant rotation of the flexibleshafting 138 will have no effect in driving worm gear 166 becauserotation of the just-mentioned enclosed shafts will have no drivingeffect upon the shaft 184 extending into the opposite end of themagnetic clutch 186. As a result, when the magnetic clutch isde-energized, rotation of pulley 110 and shaft 112 from the motor 164will simple cause the worm shaft 166 to be rotated step by step. Thespeed of this movement will be of the order of ten steps per second and,on each step, the drum will move forward by the distance between thecenters of two adjacent data-receiving cells or areas. Overrunningclutch 164 is of such design that when worm shaft 166 is being rotatedstep by step by the action of pawl 154 no drive will be transmitted fromshaft 146 to shaft 186. This action of overrunning clutch 164 relievespawl of the load of driving the drive adaptor 182.

In order to disengage the step-by-step drive of worm gear 166, the pawlthrow-out electromagnet 194, best shown in the lower central portion ofFIGURE 4, is energized so that the trip 158 fixed to its armature willbe lifted as viewed in FIGURE 9 to thereby swing pawl 150counterclockwise against the action of the spring 152. As hashereinbefore been explained, the result of this will be that shaft 146will not be driven by the pawl despite the fact that pulley 1111 may berotated by motor 168 and regardless of whether the one-revolution clutch116 may be actuated by its electromagnet 118. With the drive mechanismin this condition, and with the magnetic clutch 186 energized, rotationof pulley 110 and shaft 112 by motor 164 will result in a drive throughdrive adaptor 1%, flexible shaft 188, magnetic clutch 186,

drive adaptor 182, as well as through the overrunning clutch 164, to theworm shaft 146 and its worm gear 166. This drive will be by continuousrotation at the speed of the motor 164 and will rotate the drum at aspeed of the order of one revolution per minute.

As has been indicated above, the carrier plate 100 is.

drawn upwardly, viz., swung clockwise about its pivot 102, as viewed inFIGURE 4, by the action of spring 167. One end of spring 167 isconnected to a pin 196 fixed to the upper free corner of carrier plate100 and the opposite end of the spring is adjustably connected to abracket 198 fixed to the frame wall 34. In order to control upwardmovement of carrier 100 downwardly to place the worm gear 166 in eitherloose or tight meshing relation with the worm wheel 56 of drum 38, or tomove it downwardly to completely disengage worm gear 166 from worm wheel56, the mechanism described immediately below is provided.

As is best shown in FIGURES 4, and 6, a motor 109 and speed reducer 202are fixed to a plate 204 which, in turn is fixed to the vertical wall ofa forward extension 206 of the forward frame wall 26. As best shown inFIGURE 6, the driven shaft 208 of the gear reducer 202 extendsdownwardly. At its lower end shaft 208 has a fitting 210 fixed theretoin which the upper end of a shaft 212 is slidably keyed. In other words,while shaft 212 is free to move upwardly and downwardly with respect tothe fitting 210 and shaft 208, shaft 212 must rotate with shaft 208 andfitting 210. The portion of shaft 212 below fitting 210 is threaded and,adjacent its lower end, shaft 212 is threadedly engaged in a bore formedin a block 214 also fixed to the motor supporting plate 204. As aresult, rotation of threaded shaft 212 with shaft 208 will cause it tomove upwardly or downwardly in block 214 and fitting 210, depending uponits direction of rotation with motor 109, which is reversible.

It will be observed that because motor 109 controls the position of worm166 with respect to the drum worm wheel 56, motor 109 may be regarded asa worm or drum drive positioning motor.

A horizontal plate 216 fixed to the motor supporting plate 204 carries apair of adjustably positioned set screws or limit stops 218 and 220which are respectively adapted to cooperate with switch actuatingplungers 222 and 224. The plungers 222 and 224 respectively form theoperating elements of microswitches 226 and 223 fixed to the upper edgeof carrier plate 100, preferably upon the opposite side or face of thecarrier from that on which the abovedescribed worm driving mechanism ismounted. The threaded shaft 212 also has a disc 230 adjustably fixedthereto and which is adapted to cooperate with the actuating plunger 232of a microswitch 234 fixed to the motor supporting plate 204. The lowerend of threaded shaft 212 is adapted to engage a block or lug 236 whichextends forwardly from carrier plate 100. As is shown in FIGURES 5 and8, lug 236 also projects from the face of the carrier plate other thanthe face which carries the worm driving mechanism hereinbeforedescribed.

When the carrier plate 100 is in the upward position shown in FIGURE 4,switch 226 will be open because its plunger 222 will be in its extremeinward or downward position. Switch 226, which may be termed the fulldisengagement switch, closes or makes contact when its plunger moves tofully upward position with respect to the casing of plunger 222, and theplunger cannot reach that position until worm 166 is fully disengagedfrom worm wheel 56.

The action of motor 109 and threaded shaft 212 to swing the carrierplate 100 downwardly is as follows: When it is desired to move the wormgear 166 of worm shaft 146 entirely out of engagement with the wormwheel 56 of drum 38, motor 109 is energized to rotate shaft 208 andfitting 210 in such direction that rotation of threaded shaft 212 willcause the latter, by reason of its threaded engagement with block 214,to move downwardly.

The downward movement of threaded shaft 212 will act upon the lug 236fixed to the carrier plate 100 to swing the plate downwardly orcounterclockwise, as viewed in FIGURE 4, about its pivot stud 102. Thedriving action of motor 109 will continue until the downward swingingmovement of carrier plate 100 has proceeded far enough to permit theactuating plunger 222 of switch 226 to move outwardly or upwardly withrespect to switch 226 to thereby break the driving circuit 8 of motor109. Because the worm gear 166 is now entirely free of worm wheel 56 ofdrum 38, the latter can be rotated at high speed by the action of itsdriving motor 36.

It is desirable to enable the carrier plate to be swung upwardly tobring worm gear 166 into loose engagement with worm wheel 56 that thedrum 33 can be driven at relatively slow speed and by continuousmovement or to bring worm 166 into tight engagement with worm wheel 56so that drum 38 can be driven step by step. Certain controls forautomatically effecting such operation, as well as downward movement,are hereinafter described but, in general, the action is as follows: Toswing carrier 100 and worm 166 upwardly, the driving circuit for wormpositioning motor 109 will be energized to rotate threaded shaft 212 insuch direction as to cause it to rotate upwardly through block 214. Thisupward movement of shaft 212 will permit spring 107 to swing carrierplate 100 upwardly, but this upward swing will, of course, be limited bythe engagement of shaft 212 with lug 236 fixed to carrier plate 100. Asis hereinafter explained, during upward movement of carrier plate 100and worm 166 the actuating plunger 224 of microswitch 228 will contactwith stop 220, at which time switch 228 will be opened. Switch 228 isclosed when its plunger 224 is in its extreme outward or upward positionwith respect to the plunger casing and is opened when plunger 224 isdepressed with respect to the switch. Stop 220 will be adjusted to aposition wherein it will open switch 223 when carrier plate 100 swingsupwardly sufficiently far to cause worm 166 to be positioned in loosedriving engagement relationship with worm wheel 56 of drum 38 and theswitch will remain open during further upward movement of the carrier.'In the loose driving engagement, the two gears will be out of close ormaximum mesh with each other by a distance of the order of severalthousandths of an inch, so that they will have such a drivingrelationship that the drum can be rapidly rotated without undueresistance between gears 166 and 56.

When drum 38 is to be driven step by step, it is desirable that wormgear 166 closely and tightly engage the worm wheel 56 so that anydesired cell or area on the drum can be brought into exactly alignedposition with an erasing and recording magnet 60 for recording purposes.By this arrangement, there will be no possibility of correspondingmagnetized areas being out of a desired alignment of registry. In orderto bring worm gear 166 and worm wheel 56 into this tight meshingengagement the circuit to motor 109 is closed to cause it to rotate insuch direction as to draw threaded shaft 212 further upwardly throughblock 214. Such rotation will be continued until carrier plate 100 hasswung upwardly under the influence of spring 107 a sufiicient distanceto permit worm gear 166 to tightly engage worm wheel 56. Rotation ofshaft 212 will continue for an instant after this occurred and so thatthe lower end of the shaft will move entirely out of engagement with thelug 236 of carrier plate 100. Then the disc 230 fixed to the threadedshaft 212 will engage the plunger 232 of the microswitch 234 to movethat plunger upwardly or inwardly to thereby break the driving circuitof motor 109. As is indicated in FIGURE 12, the contact 212' carried bythe plunger of switch 234 has two fixed contacts 234A and 2348 in itspath. Contact 234A will be engaged by the plunger contact 212' when worm166 and worm wheel 156 are tightly engaged, while contact 23413 will beengaged when the two worm gears are either in loosely engaged positionor fully disengaged position, as well as in positions intermediate thetwo last-mentioned positions.

DRIVE CONTROLLING CIRCUITS FIGURES l2 and 13 diagrammatically show thecontrol circuits and elements whereby drum 38 will be connected to oneof the several sources of power and then driven as best suited for eachof the several principal operations of the drum. These severaloperations are (a) high-speed reading or analyzing of data which hasbeen recorded upon the drum, (b) high-speed recording, (c) high-speedenasing of data from the drum, and (d) at low speed, either recordingnew data upon the drum or altering data which has already been recordedupon the drum.

As is hereinafter explained, the drum will be rotated continuously at aspeed of the order of 220* rpm. when operations (a) to (c) are to beperformed. In order to connect drum 38 to the high speed driving motor36 for this type of drive, the control circuits and elements of FIGURES12 and 13 operated in approximately the same manner. However, whenoperation (d), viz., the stepby-step or slow speed recording or alteringof data, is to be performed, the connection of the drum to thestep-bystep driving means through worm 166 can be carried out under anyone of three conditions. These three conditions are hereinafter termedAutomatic Homing, Recycle and Non-Homing.

Generally speaking, the matter of which of the three conditions will beused to obtain the drive used during operation (d) will depend on howdrum 38 is connected to the driving means at the moment when it isdesired to change over to operation (d), or whether the operator wishesto bring the starting or Homing point of the drum into alignment withthe magnets. However, once the circuits of FIGURES 12 and 13 have beenactuated under the selected condition to provide the drive for operation (d) the drive of the drum during that operation will always bethe same, viz., at the rate of approximately ten stepped movements persecond.

FIGURE 14 diagrammatically indicates the sequence of the operation ofthe various elements of the control circuits, including relays R1 to R9and the switches 226, 228, 234, 244, and 248, during operations (a),(b), (c) and (d). However, while FIGURE 14 shows the action of all ofthe elements in the proper relationship to each other, the time durationof those actions is not accurately proportioned in the figure.

The matter of whether the circuits are to be operated for use of thedrum for (a) high speed reading, (b) high speed erasing, or (d slowspeed recording or alteration, is determined by an Operation Selectionswitch OS indicated in FIGURE 12 and comprising three blades O31, CS2,and 083 which are connected to pivot together but are insulated fromeach other. In order to select which of the three conditions will beused to bring worm 166 into tight engagement with drum worm wheel 56 forstep-by-step drive during operation (d), above, there is provided(FIGURE 12) the Condition Selector switch CS. Switch CS includes threeblades CS1, CS2, and CS3 which also pivot together but are insulatedfrom each other.

In connection with FIGURES 12 and 13, it may be stated that thefollowingsystetm is used in designation of the movable contacts of therelays R 1 to R9: Each contact blade reference character has the letterC, and the first number of the reference character corresponds to therelay number. The second number of each reference character is an evennumber if the contact is open when the relay is =de-energized, and is anodd number if the contact is normally closed when the relay isdeenergized.

FIGURES 12 and 13 illustrate Operation Selector switch OS at Recording,and Condition Selector switch CS at Automatic Homing. However, itassumes that these switches have just been moved to that position and,therefore, shows relays R1 to R9 de-energized, switches 244 and 248 intheir normal condition, and switches 226, 228 and 234 in the positionthey occupy when worm 166 is fully disengaged from drum worm wheel 56.Leads extend between FIGURES 12 and 13, and the lower edge 10 of FIGURE12 must be aligned with the upper edge of FIGURE 13.

Drive Controlling Circuits-Reading--Worm Initially in DisengagedPosition Referring to FIGURE 12, if reading or analyzing of the dataupon the drum 33 is to be performed, the Operation Selector switch OSwill be moved to bring its blades O81, OS2, and 083 respectively intoengagement with the fixed contacts 3111, 302, and 3113, which are theReading contacts of that switch. The operator will then momentarilyclose the starting switch S3. If worm 166 is in fully disengagedposition, i.e., entirely out of engagement with the drum worm wheel 56,so that the contact movable with plunger 222 of full disengagementswitch 226 shown in the upper left-hand portion of FIGURE 12 is inengagement with fixed contacts 226A and 226A, the following circuit willbe closed when starting switch S3 is closed: From one conductor 3114(top of FIGURE 13) of a 60 volt DC. line, by lead 3115 extending (FIGURE12) to the fixed contact 226A, through the contact blade of switch 226to fixed contact 2526A, and thence by leads 306 and 3117 to blade 081 ofswitch OS, by contact 301 and lead 368 through normally closed stopswitch S4, lead 309 to contact 3113 of starting switch S3, through theclosed contact of that switch to contact 311, by leads 312 and 313 tothe coil of relay R1 and thence by lead 314 to the other conductor 315of the 60 volt D.C. line.

The energization of relay R1 will cause its normally open contacts C10,C12, C14, and C16 to close. The closing of contact C19 Will set up aholding circuit by lead 316, across the now closed contact C10 and byleads 317 and 313, through the coil of relay R1 so that the startingswitch may open, and the relay will be held energized until stop switchS4 is opened.

Independently of the closing of starting switch S3 or any operation ofswitch OS, the fact that worm carrier 1% and worm 166 are completelydisengaged from drum worm wheel 56 will cause full disengagement switch226 to be closed as shown in FIGURE 12. The fact that switch 226 isclosed will cause relay R2 to be energized as follows: From conductor3134 of the 60 volt D.C. line, lead 3115, switch 226 and lead 396through the coil of relay R2 (FIGURE 13) and by lead 318 to conductor315. Because relay R2 is energized, its contact C21 will be open. Bybeing open, contact C21 will hold open a circuit through the wormpositioning motor controlling relay R4, and which circuit would beclosed if relay R2 were not energized and its contact C21 remainedclosed. The significance of this action is subsequently explained.

Referring again to the relay R1, when this relay is held energized asexplained above, the motor 36 which drives the drum shaft 37a and drum38 by continuous rotation at relatively high speed will be powered bythe following circuits through the contacts C12 and C14 of relay R1:From the conductor 320 of a 220 Volt AC. line (center of FIGURE 12)across the closed contact C12, by lead 321 to motor 36, and thence bylead 322 across the closed contact C14 to the other conductor 323 of the220 volt A.C. line.

Energization of relay R1 also causes the magnetic brake 44 whichnormally engages drum shaft 37a to be released by the following circuitcontrolled by contact C16 of relay R1: From conductor 326 of volt D.C.line (lower right-hand corner of FIGURE 12) by lead 327, contact C16,leads 328 and 329, through the electromagnetic coil 440 to disengagebrake 44 and thence by lead 330 to the other conductor 331 of the 110volt D.C. line.

The above operations initiated by the closing of starting switch S3 areindicated in FIGURE 14 under the heading Read appearing in the upperleft-hand corner of FIGURE 14 and under the legend Move Switch OS toRead and Close Start Switch S3. In vertical order under this legend, theenergization of the relay R1 is in-

1. IN COMBINATION, A BASE, A DATA RECEIVING PARAMAGNETIC ELEMENT MOVABLEWITH RESPECT TO SAID BASE, DATA TRANSMITTING MEANS INCLUDING A MAGNETPOSITIONED ADJACENT THE PATH OF MOVEMENT OF SAID ELEMENT, SELECTIVELYOPERABLE DRIVE MECHANISM TO MOVE SAID ELEMENT EITHER AT HIGH SPEED OR ATLOW SPEED TO A PREDETERMINED EXTENT, MEANS OPERABLE UPON MOVEMENT OF THEELEMENT TO SAID EXTENT TO CAUSE THE LOW SPEED MOVEMENT TO BE STEP BYSTEP IN STEPS OF UNIFORM LENGTH TO A FURTHER EXTENT, AND MEANS